Constant temperature heater



FIG. 1 is a front elevational view of a constant temperature heater showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a top, front and right side perspective view thereof; and,

FIG. 8 is a top, rear and left side perspective view thereof.

The broken lines in the drawings illustrate portions of the constant temperature heater which form no part of the claimed design. 

CLAIM The ornamental design for a constant temperature heater, as shown and described. 